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INSE 7110 – Winter 2008 Added Services Engineering in Next users.encs. glitho//W08_Lect3.pdf · PDF file 2008. 1. 21. · 12 Roch H. Glitho- Ericsson/Concordia University January

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  • 1 Roch H. Glitho- Ericsson/Concordia University January 2008

    INSE 7110 – Winter 2008 Added Services Engineering in Next Generation Netw

    Lecture 3, Week #3

  • 2 Roch H. Glitho- Ericsson/Concordia University January 2008

    Outline

    1. Introduction 2. Core SIP 3. Selected Extensions 4. Third Generation Cellular

    Networks

  • 3 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: Introduction

    A set of IETF specifications including: – SIP core signalling:

    • RFC 2543, March 1999 • RFC 3261, June 2002 (Obsoletes RFC 2543)

    – SIP extensions (e.g. RFC 3265, June 2002 - Event notification)

    • May have nothing to do with signalling

    – Used in conjunction with other IETF protocols • QOS related protocol (e.g. RSVP) • Media transportation related protocol (e.g.

    RTP - RFC 1889) • Others (e.g. SDP - RFC 2327)

    .

  • 4 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: Introduction

    Prime signaling system because adopted by all key next generation networks: – 3GPP – 3GPP2 – PacketCable:

    .

  • 5 Roch H. Glitho- Ericsson/Concordia University January 2008

    Session Initiation Protocol (SIP) - Core

    1. Introduction

    2. Functional entities

    3. Messages

    4. A digression on SDP

    5. Examples

    .

  • 6 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: Introduction

    SIP core Signaling – A signalling protocol for the establishment,

    modification and tear down of multimedia sessions – Based on HTTP

    A few key features – Text based protocol – Client/server protocol (request/response protocol)

    .

  • 7 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: The functional entities

    User agents - End points, can act as both user agent

    client and as user agent server - User Agent Client: Create new SIP

    requests - User Agent Server: Generate

    responses to SIP requests - Dialog: Peer to peer relationship between

    two user agents, established by specific methods

    Proxy servers - Application level routers

    Redirect servers - Redirect clients to alternate servers

    Registrars - Keep tracks of users

    .

  • 8 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: The functional entities

    State-full proxy

    - Keep track of all transactions between the initiation and the end of a transaction

    - Transactions: - Requests sent by a client along with all

    the responses sent back by the server to the client

    Stateless proxy - Fire and forget

    .

  • 9 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: The messages

    Generic structure - Start-line - Header field(s) - Optional message body

    Request message - Request line as start line

    . Method name

    . Request URI

    . Protocol version

    Response message - Status line as start line

    . Protocol version

    . Status code

    . Reason phrase (Textual description of the code)

    .

  • 10 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: The messages

    Request messages - Methods for setting up sessions

    . INVITE

    . ACK

    . CANCEL

    . BYE

    - Others . REGISTER (Registration of contact

    information) . OPTIONS (Querying servers about their

    capabilities)

    .

  • 11 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: The messages

    Response message - Provisional - Final

    Examples of status code 1xx: Provisional 2xx: Success 6xx: Global failure

    .

  • 12 Roch H. Glitho- Ericsson/Concordia University January 2008

    A digression on SDP …

    Session Description Protocol - Convey the information necessary to allow a

    party to join a multimedia session Session related information Media related information

    - Text based protocol

    - No specified transport - Messages are embedded in the messages

    of the protocol used for the session - Session Announcement Protocol (SAP) - Session Initiation Protocol (SIP)

    .

  • 13 Roch H. Glitho- Ericsson/Concordia University January 2008

    A digression on SDP …

    Session Description Protocol - = - Some examples

    Session related v= (protocol version) s= (Session name)

    Media related m= (media name and transport address) b= (bandwidth information)

    .

  • 14 Roch H. Glitho- Ericsson/Concordia University January 2008

    A digression on SDP …

    Session Description Protocol Use with SIP - Negotiation follows offer / response

    model - Message put in the body of pertinent

    SIP messages INVITE Request / response OPTIONS Request / response

    .

  • 15 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: A simplified call case

    .

    INVITE (1)

    INVITE (2)

    INVITE (4)100 TRYING (3)

    100 TRYING (5)

    180 RINGING (6)

    180 RINGING (7)

    180 RINGING (8) 200 OK (9)

    200 OK (10)

    200 OK (11)

    ACK (12)

    MEDIA SESSION

    BYE (13)

    200 OK (14)

    CALLER PROXY A PROXY B CALLEE

  • 16 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: Examples of messages from the RFC

    An example of an INVITE

    INVITE sip:[email protected] SIP/2.0 Via: SIP/2.0/UDP

    pc33.atlanta.com;branch=z9hG4bK776asdh ds

    Max-Forwards: 70 To: Bob From: Alice

    ;tag=1928301774 Call-ID:

    [email protected] CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 142

    .

  • 17 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: Examples of messages from the RFC

    An example of an OPTIONS message

    OPTIONS sip:[email protected] SIP/2.0 Via: SIP/2.0/UDP

    pc33.atlanta.com;branch=z9hG4bKhjhs8ass 877

    Max-Forwards: 70 To: From: Alice

    ;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 63104 OPTIONS Contact: Accept: application/sdp Content-Length: 0

    .

  • 18 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP: Examples of messages from the RFC

    An example of RESPONSE to the OPTIONS request

    SIP/2.0 200 OK Via: SIP/2.0/UDP

    pc33.atlanta.com;branch=z9hG4bKhjhs8as s877

    ;received=192.0.2.4 To:

    ;tag=93810874 From: Alice

    ;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 63104 OPTIONS Contact: Contact: Allow: INVITE, ACK, CANCEL, OPTIONS,

    BYE Accept: application/sdp Accept-Encoding: gzip Accept-Language: en Supported: foo Content-Type: application/sdp

  • 19 Roch H. Glitho- Ericsson/Concordia University January 2008

    SDP: Examples of messages from the RFC …

    Session Description Protocol An example from the RFC … v=0 o=mhandley 2890844526 2890842807 IN IP4

    126.16.64.4 s=SDP Seminar i=A Seminar on the session description

    protocol

    u=http://www.cs.ucl.ac.uk/staff/M.Handley/sdp.0 3.ps

    [email protected] (Mark Handley) c=IN IP4 224.2.17.12/127 t=2873397496 2873404696 a=recvonly m=audio 49170 RTP/AVP 0 m=video 51372 RTP/AVP 31 m=application 32416 udp wb a=orient:portrait

  • 20 Roch H. Glitho- Ericsson/Concordia University January 2008

    SIP – Selected Extensions

    1. Extensions for ad hoc networks

    2. Event framework

    3. Others

    .

  • 21 Roch H. Glitho- Ericsson/Concordia University January 2008

    Ad hoc networks

    (Possibly mobile) heterogeneous nodes communicating without fixed infrastructure and pre-set organization of available links - Wireless technologies (e.g. Bluetooth, IEEE

    802.11) - Used in scenarios such as:

    - Disaster relief operations - Military operations - Hot spots …

    - Considered a a new network of 4G - 4G

    - Co-existing and cooperating networks

    .

  • 22 Roch H. Glitho- Ericsson/Concordia University January 2008

    Ad hoc networks

    Signalling - No centralized entity - Dynamic propagation of session related

    information - Scalability - Lightweight - Optimal usage of resources

    .

  • 23 Roch H. Glitho- Ericsson/Concordia University January 2008

    Ad hoc networks

    Signalling - Possible, but not optimal implementation:

    Full-mesh

    .

  • 24 Roch H. Glitho- Ericsson/Concordia University January 2008

    Ad hoc networks

    Signalling – Extensions made to SIP - Expired IETF drafts

    - Example of new headers - Also: List the participants already connected to

    the session or trying to connect to it - Replace: use in split / merge operation

    - Listed participants should be treated as if they have sent a BYE to the recipient of the message

    .

  • 25 Roch H. Glitho- Ericsson/Concordia University January 2008

    Event Notification

    Motivation - Necessity for a node to be asynchronously

    notified of happening (s) in other nodes - Busy / not busy (SIP phones)

    - A client A can call again a client B when notified that B is now